Need advice on Tuning a Quad

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gsuburban

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1989
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That quadrajet also needs to confirm the float position with the carb kit measuring tool. A low float can make it lean as well. The idle mixture screws have nothing to do with above idle mixtures which means the metering rods need to be checked for proper flow. Also, the secondaries have an upper butterfly that controls how soon the added air feeds into the secondary throttle plates which those dump tubes feed. Its difficult to see when those butterflies open under load however, if there is a need to adjust them to open sooner or later, there is a tiny allen screw under the choke pull down linkage on the right side of the butterfly rod. If the idle is good, 650 to 700, RPM you won't need to do anything with the initial base idle screw which is hidden on unaltered carbs. There are many adjustments and many tiny air bleeds that have to be free and clear of dirt for it to function.
 

gsuburban

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On most GM's, that era, vacuum advance works from "manifold vacuum" so the vacuum line to the distributor must connect to the "T" fitting on the manifold just ahead of the carb. Total advance should be checked with the vacuum hose OFF and temporarily plugged. Vacuum advance is for drivability and fuel mileage as well as heating issues. Always use manifold vacuum, NOT venturi vacuum from the quadrajet. Lots of people are confused which one to use. AND as always, change the oil and "Wix XP" filter every 5,000 miles, 100% synthetic if possible.
 

Ricko1966

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On most GM's, that era, vacuum advance works from "manifold vacuum" so the vacuum line to the distributor must connect to the "T" fitting on the manifold just ahead of the carb. Total advance should be checked with the vacuum hose OFF and temporarily plugged. Vacuum advance is for drivability and fuel mileage as well as heating issues. Always use manifold vacuum, NOT venturi vacuum from the quadrajet. Lots of people are confused which one to use. AND as always, change the oil and "Wix XP" filter every 5,000 miles, 100% synthetic if possible.
His isn't most gm from this Era it's knock sensor esc equipped 305,he'd have to check total with esc bypassed but they ran these with more total because the esc was going to pull timing as needed. I messed with mine for 2 years IDK how long @SirRobyn0 messed with his,in the end factory or as close to factory as.possible is what works best overall.
 
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